﻿A new species and a new provincial record of the genus Acidota Stephens from China (Coleoptera, Staphylinidae, Omaliinae)

﻿Abstract New taxonomic and faunistic data for two species of the genus Acidota Stephens, 1829 from China are provided. A new species from Xizang (Linzhi) is described and illustrated: A.dawai Peng & Chen, sp. nov. Additional data (including photographs of the habitus and the type labels) on the type specimens of taxa described from Japan (A.crenatajaponica Watanabe, 1990) and Taiwan (A.montana Smetana, 1993 and A.nivicola Smetana, 1993) are given. A key to Chinese species of Acidota is given. Acidotacrenata (Fabricius, 1792) is recorded from Heilongjiang for the first time.


Introduction
Until now, eight species of the genus Acidota Stephens, 1829 have been reported from the Nearctic and Palaearctic regions (Smetana 1993;Assing 2002;Shavrin 2021). According to Shavrin (2019Shavrin ( , 2021, the speciose omaliine genus Acidota is represented by seven described species in the Palaearctic region, three of which have been reported from China. Two species were described from Taiwan: A. montana Smetana, 1993 from Nenkaoshan and A. nivicola Smetana, 1993 from Hsuehshan (Smetana 1993). Shavrin (2019) recorded A. crenata (Fabricius, 1792) from Gansu, China. This paper presents taxonomic and faunistic data for four Chinese species, including one new species (Acidota dawai Peng & Chen, sp. nov.) from Xizang and a new faunistic record of A. crenata. A key to the Chinese species of Acidota is provided. Additional data from the type of A. crenata japonica Watanabe, 1990 is given.

Material and methods
The examined material is deposited in the following public collections: The genitalia and other dissected parts were mounted on plastic slides and attached to the same pin as the respective specimens. Photographs were taken with a Canon EOS 7D camera with an MP-E 65 mm macro lens or with a Canon G9 camera mounted on an Olympus CX31 microscope.

SNUC
The following abbreviations are used in the text, with all measurements in millimeters: Total length (TL) length of body from anterior margin of mandibles (in resting position) to abdominal apex. Length of forebody (FL) length of forebody from anterior margin of mandibles to posterior margin of elytra. Head length (HL) length of head from anterior margin of frons to posterior constriction of head. Head width (HW) maximum width of head. Antenna length (AnL) length of antenna from the base to the apex. Pronotum length (PL) length of pronotum along midline. Pronotum width (PW) maximum width of pronotum. Elytral length (EL) length at suture from apex of scutellum to elytral hind margin. Elytral width (EW) combined width of elytra. Length of aedeagus (AL) length of aedeagus from apex of ventral process to base of aedeagal capsule.
Pronotum slightly transverse, widest in the middle; disc convex, without impression; punctures similar to that of head, but more distinct; pubescence moderately long and dense.
Elytra slightly convex, 1.1 times as wide as long; punctation coarser and sparser than that of pronotum; pubescence distinctly sparser than that of pronotum. Hind wings well developed.
Abdomen slender, widest at segment V, evenly narrowing posteriorly. Abdominal tergites with fine and dense punctation, and short decumbent pubescence, denser on apical tergites; tergites IV-V with a pair of tomentose spots in middle, spots on tergite V smaller and less transverse.

Male.
Posterior margin of abdominal tergite VIII (Fig. 3C) and sternite VIII (Fig. 3D) truncate. Aedeagus as in Fig. 3E, F; median lobe indistinctly narrowed toward moderately wide with subacute apex; parameres symmetrical, wide, reaching apex of median lobe, each bearing two apical setae; internal sac wide and long, spirally folded in basal portion.
Distribution and natural history. The type locality is situated in the Sejila Mountain to the east of Linzhi, south-eastern Xizang. Some of the specimens were sifted from rhododendron litter and humus in a rhododendron forest on a west slope near the mountain summit at an altitude of 4340 m (Fig. 3G).
Etymology. This species is dedicated to Mr Dawa, who supported us on our field trips.
Comparative notes. Regarding the general shape of the body, aedeagus, and features of the punctation and pubescence, A. dawai is similar to dark-coloured specimens of the morphologically variable A. crenata, a widespread species in the Holarctic region. The new species can be distinguished from A. crenata by the distinctly more transverse head, longer antennomere 2, and the shapes of the slightly wider and shorter parameres, which are subparallel in the middle and gradually narrowing towards the apex (parameres of A. crenata are insignificantly narrower, moderately strongly narrowing apicad). Comment. Habitus as in Fig. 4A. This species is known only from Taiwan (Smetana, 1993). For illustrations of A. montana see Smetana (1993: figs 1-3).   Fig. 4B. This species is known only from Taiwan (Smetana, 1993). For illustrations of A. nivicola see Smetana (1993: figs 6, 7). Smaller species (length of body: 4.5 mm). Aedeagus narrower, apex of median lobe narrowly subtruncate. Habitus as in Fig. 4B. Taiwan